This invention relates to support tapes of a slide fastener. More particularly, the invention relates to support tapes of warp-knit material which are stretchable at side areas opposite the fastener element mounting areas so that the tapes may be easily bent in the plane including the tapes.
When a slide fastener is mounted so that it is bent in the plane including the support tapes thereof, the outer side portions of the tapes should be expandable lengthwise. Heretofore, in either woven tapes or knitted tapes, such strechability has been attained by elastic yarns forming a part of woven or knitted structure and disposed to extend in the direction in which the tapes should stretch. One example of such strechable tape is disclosed in U.K. Pat. No. 1,396,577. When support tapes using elastic yarns are fixed along a way which is bent in the plane including the tapes, the outer tape at a corner of the way is secured by, for example sewing, to a member on which a slide fastener is to be mounted while the outer tape is longitudinally stretched. The stretched tape tends to return to its original position and this creates substantial force. Therefore, there is a problem that upon release of the force for stretching the tape after sewing, the portion of the member to which the tape is secured at the corner corrugates together with the tape resulting in impaired appearance. Furthermore, due to the high elastic constant of the elastic yarns, a relatively large tensile force remains after sewing in the outer tape at the corner. Therefore, another problem is that this tensile force adversely affect the position of the fastener elements and may make the interengagement unreliable.